


Take the Devil Out of Me

by Kindassunshine



Category: Ao no Exorcist | Blue Exorcist
Genre: Anal Sex, Canon-Typical Violence, Demons, Dubious Consent, Dubious Morality, M/M, Mating Cycles/In Heat, Rough Kissing, Rough Sex, Tails, Vomiting, Voyeurism
Language: English
Status: Completed
Published: 2017-02-16
Updated: 2017-02-16
Packaged: 2018-09-25 00:11:06
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,659
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9793826
Author URL: https://archiveofourown.org/users/Kindassunshine/pseuds/Kindassunshine
Summary: ‘Why don’t you just lay there, Exorcist,’ Amaimon hissed softly into his ear. When he was sure the man would not move again Amaimon leaned back yanking Rin’s hips up and twisting his tail around his forearm.Rin whined but didn’t dare move too much with his tail pulled taught. Amaimon was leaning over him, nails tracing over Lightning’s forehead. Yukio could see his eyes flicker.‘Touch me,’ Amaimon murmured, running a pointed tongue over his sharp incisors.In desperation, to protect Rin, Yukio is forced to ask the unspeakable from the Earth King and Mephisto is playing games of his own.





	

**Author's Note:**

> This work technically has a prequel (you might be able to guess which one from the name) which has similar content but I wrote it three years ago so I didn't want to alarm anyone with the sudden change in writing style... so here we are :D 
> 
> Enjoy!

‘He better be dying,’ Mephisto yawned theatrically, ‘some of us need our beauty sleep, you know.’ Somehow he managed to growl even though the tinny phone speaker.   
‘Forgive me, sir – I didn’t know who else…’ Yukio bit his lip, trying to keep the rising panic out of his voice. He’d been woken about half an hour ago by Rin’s hot hand over his month. His brother had been shaking, feverish, his skin too sensitive to touch.   
‘It’s been barely six months,’ Mephisto grumbled.  
‘Does that mean it’s getting worse?’ Yukio asked worriedly, turning toward the bathroom at the sound of a pained whine.   
‘It means your brother is an insatiable brat,’ a sigh at the other end of the line, ‘I’ll be there as quickly as I can.’ Yukio opened his mouth to speak but the call was cut sharply. He glanced around expecting his superior to pop into existence any moment.   
‘Yukio,’ came Rin’s soft moan from the bathroom. Yukio walked slowly over, pausing on threshold, feeling the humidity leaking from the bathroom on his skin. He knew it wasn’t fair but he didn’t want to look at Rin at the moment, not while his brother barely looked human.   
In an attempt to cool him down Yukio had run a cold bath, bringing ice cubes from the kitchen, but the most of the water had evaporated as soon as it touched his brother’s flushed skin.   
‘Mephisto is on the way,’ he murmured through the slight gap in door. Rin groaned and Yukio could see him, naked, crouched on all fours in the remaining water, back arching and tail twitching restlessly. He leaned his forehead against the doorframe, exhaling carefully. Whatever Mephisto said Rin shouldn’t be in this state again so soon.   
There was sharp rap behind him and Yukio moved quickly to the door. If he was surprised by Mephisto actually knocking he was astounded by the trio standing causally on the landing.   
‘Hey, Yukio,’ drawled Lewin Light strolling into the room followed by a pyjama-clad Mephisto and expressionless Amaimon. Yukio looked between Mephisto and the Arc Knight wondering if he was hallucinating. Mephisto shook his head refusing to answer the unasked question, remarkably grave for a person dressed head-to-toe in lilac sateen.   
The man had already moved towards the bathroom, giving a low whistle at the sight of Rin.   
‘How long has he been like this?’ Mephisto murmured crossing the room, standing shoulder to shoulder with the other exorcist.   
‘A couple of hours, I think,’ Yukio muttered glancing back to where Amaimon stood, uncomfortable with the thought of the Earth King at his back.  
‘Here,’ Mephisto clicked and Amaimon stumped over.   
‘I don’t want to help him,’ he complained as Mephisto pushed him ahead of them into the bathroom.   
‘Ah, but look at him now,’ Mephisto sighed, ‘doesn’t it make even your heart melt with pity, baby brother?’ Amaimon frowned a little and Yukio wondered if he knew what the word pity meant.   
And Rin did look pitiful, he had to admit, curled against tiles at the other end of the bath flushed and panting as though he’d just run a marathon. His eyes were unfocused and Yukio could see the sweat rising on his skin.   
‘Looks like he’s about to blow,’ Lightning murmured. He bent dipping his hand in the swallow water and flicking it at Rin, who hissed softly. Wherever the water touched his skin it evaporated instantly sending up a tiny plume of steam.   
‘That –,’ he cackled, repeating the action, ‘is wicked.’ Yukio looked desperately at Mephisto.   
‘Have you seen enough?’ Mephisto muttered to the man crouched beside the tub. Lightning looked up at him with a smirk but before he could speak Rin unfurled himself.  
‘Am I going to die?’ he gasped, half staggering towards Mephisto who regarded him indifferently.   
‘Not tonight,’ he told him, pushing Rin away by the top of the head so he landed back in the water on his rump.  
‘Then why is this –’ Rin choked.  
‘Didn’t the old man tell you about the birds and the bees?’ Mephisto shrugged, perching on the lip of the bath now. Glancing at him Yukio noticing he really did look tired.   
‘I don’t get it,’ Rin mumbled, glancing at his brother. His mouth was wet, deep pink and half open so Yukio could just see the tips of his fangs.   
‘You are what you are,’ Mephisto murmured swirling a long-nailed hand in the tepid water. Rin sighed, face relaxing a little and Yukio realised he must have done something. ‘You’re just going to have to accept that you’re hyperactive.’ The temperature of the bathroom seemed to be rapidly dropping now.   
‘You’re one scary guy, Mr Pheles,’ Lightning chuckled, his exhale leaving a white cloud on the cool air. Yukio shivered.  
‘Is that so?’ Mephisto snorted softly. His shadowed eyes moved back to Rin, ‘is there anything you can do?’  
‘Me?’ Lightning grinned, ‘not my area of expertise, I’m afraid. Azazel ain’t ever come to me with that kind of problem.’ Yukio flinched as Amaimon made sudden convulsive movement and Mephisto cut him a sharp look. He muttered something in their own scratchy language and Mephisto hissed back at him. Yukio pulled his pistol half on instinct.   
‘Hey!’ Lightning barked as Rin gasped covering his ears as though hearing the words hurt him. ‘Got quite a mouth on you, huh?’ he growled, twisting so he stood between Amaimon and Rin. Amaimon snarled.   
‘Wanna go back to Gehenna kid?’ the man smirked, tracing a circle in the air between them his fingertip leaving the slightest trace of phosphorescence. Amaimon growled softly, licking his teeth and lowering his chin.   
‘Enough!’ Mephisto snapped, clapping as though to scare pigeons. Amaimon ignored him but Lightning chuckled pushing his hat back. He snapped his fingers once dismissing the circle and Yukio let out his breath in relief.   
As he lowered his gun, Yukio’s heart was pounding. He was crouched in the corner braced with his back against the bathroom door, not keen to get between an Arc Knight and a Demon King.   
‘Go back to my office,’ Mephisto sighed, pulling a key on a thin gold chain over his head and holding it out to Amaimon. The Earth King didn’t move.  
Finally he broke off his glare and bowing his head, hands folded. The image of repentance, Yukio thought unconvinced.   
‘Please, brother,’ he murmured, ‘I’ll behave.’  
‘You will,’ Mephisto growled but before he could say anything more Rin whined his body contracting as though he’d been impaled in the stomach. Yukio quickly holstered his gun.   
‘There now,’ Lightning murmured gently, stooping to rub his knuckles over Rin’s bare shoulder and up the line of his neck and back again. Rin shivered whining, pressing into his hand. Yukio looked away feeling heat creeping up his own neck.   
‘Ah, I thought you might like a little attention from Mr Tamer,’ Mephisto chuckled, eyes on Rin’s dark hair, and Lightning laughed.  
‘You know more than me,’ he snickered, scratching Rin’s scalp now, ‘honestly I didn’t think this one liked me very much.’ Rin was looking at the man now, though Yukio thought his eyes still looked glassy. ‘That’s true, right?’ he grinned at Rin, tipping his head to the side. Rin was smiling back but it looked strange, not the one Yukio recognised. He opened his mouth to warn him but Rin had already moved. Springing like a viper he’d caught and dragged Lightning into the bath and underneath him. He planted a knee pressing either side of the spluttering exorcist’s chest.   
Yukio took a step forward but paused when he realised Lightning was laughing again.  
‘I give up,’ he chuckled, holding up his palms to a growling Rin, ‘you’re a lot stronger than you look, you know.’ He was leant back on his elbows in, what must have been, icy water lapping up to his mid-chest. He’d lost his hat and one side of his dark hair was dripping.  
Mephisto stood, apparently irritated by the splashing. To Yukio’s surprise he came to stand next him.  
‘Okay, okay,’ Lightning told him as Rin started tugging up his t-shirt, ‘let me take this off first.’ He shrugged off his jacket and letting Rin peel the t-shirt off his wet skin, his nipples puckered in the cool air.   
Yukio glanced at Mephisto’s profile suddenly concerned more clothes would be coming off. But Rin seemed satisfied with this much, wriggling into Lightning’s lap and leaning into the man’s neck as he scratched his scalp gently. Yukio tried not to think too hard about what exactly his brother was rubbing against the man’s bare stomach.   
Lightning was speaking quietly to Rin, slow and soft, as he nuzzled against him. At first Yukio thought it was an incantation but after a moment he realised he was speaking English, his smooth drawl more pronounced in his native tongue. Although, Yukio reflected, with Rin’s test scores he might as well have been quoting scripture.   
For a few moments Yukio counted the tiles on the floor and wished very sincerely he was deaf, especially when Rin started giving deep moans – at least he hoped it was Rin. He wasn’t sure if he felt better or worse about his brother curtailing his urges with his superior over the Earth King.   
His head snapped up when Amaimon moved.   
He’d stepped neatly into the tub, still wearing his curly-toed boots. The absurdity of this momentarily distracted Yukio, which was why Mephisto was able to catch his wrist when Lightning shouted.   
Amaimon had bent at the waist catching him by the chin, clawed fingertips digging in deep enough to draw blood. Rin tried to squirm out from between them but Amaimon caught him by the throat was his other hand while his eyes were fixed on the man’s.   
‘You’re fucking dead,’ Lightning barked but before he could do anything else Amaimon exhaled heavily into his mouth and something flicked at the edge of Yukio’s vision.   
Amaimon unceremoniously dropped the man back into the water. As Yukio watched Lightning’s body went rigid but then he groaned deep in his chest, back arching as his head dropped back, hips bucking up irresistibly into Rin and the now kneeling Amaimon.   
Yukio started forward but Mephisto stuck out an arm to arrest his momentum.   
‘You won’t want to get any closer,’ he murmured, ‘it might affect you.’   
‘What?’ Yukio frowned at him, glancing back trio in the bathtub. As he watched Amaimon leaned in, trapping Rin between their bodies, and kissed Lightning on the mouth. Rin squeaked as Lightning shifted forwards too deepening the kiss, tanned hand coming up to grip Amaimon’s short green hair.  
‘What did he do?’ Yukio asked disbelieving. Lighting didn’t seem to be in danger of dying but Yukio had a feeling letting the Earth King kiss him was unusual behaviour.   
‘Nothing harmful,’ Mephisto shrugged, ‘a little earthly desire.’ He smirked when Yukio continued to glare at him.  
‘Tell Amaimon to stop!’ Yukio hissed.   
‘Ah, don’t worry Mr Tamer won’t remember a thing,’ Mephisto told him waving a hand lazily, ‘and besides, he’s done worse with his own hands.’  
‘That isn’t really the issue,’ Yukio told him angrily, turning and realising Mephisto was between him and the door, ‘let me out, if you’re not going to stop this immediately I’ll–’   
‘Fine,’ Mephisto sighed and with a snap of his fingers transported them to the next room. Yukio staggered, disorientated, and a squeal of springs told him Rin and Lightning had crashed landed on the bed.   
He caught hold of the desk to right himself but before he could make a move towards Rin, his legs were knocked out from under him by a chintz armchair.  
‘Now, now Mr Okumura,’ Mephisto chuckled waving long-nailed hand elegantly at him, ‘you stay right there, can’t have you embarrassing yourself.’   
On the bed Amaimon had landed cat-like, pinning the two humans beneath him. Lightning was flat on his back clearly winded where Rin had landed heavily on his chest. Amaimon curled a hand around his chin again.  
‘He’s an exorcist,’ he murmured, pointed tongue sliding over his sharp teeth, glancing at Mephisto, ‘so I don’t have to go easy?’   
‘He’s human,’ Mephisto corrected, ‘so you need to be careful.’ He pulled up each of Lightning’s eyelids and pressed his palm to his forehead. Amaimon rolled his eyes. Yukio found it unnerving; it was perhaps the most expressive he’d seen the Earth King.   
Lightning sighed softly leaning up into the touch, back arching, ‘Mephisto,’ he murmured, voice deep and velvety. Mephisto made a soft noise but took his hand back.   
Rin moaned quietly and Yukio made to stand but Mephisto gestured him back.  
‘Get on with it,’ he grunted at his brother, settling himself on the arm of Yukio’s chair and yawning again.  
‘I’ll report you,’ Yukio muttered, jaw set. Watching as Amaimon ran a claw over Lightning’s lip.  
‘Oh please do,’ Mephisto snorted then added with a sigh, ‘if Amaimon… assists, he will be able to prevent your brother doing our dear Arc Knight any permanent harm.’   
‘Rin wouldn’t –’ Yukio started furiously.   
‘Rin is a demon,’ Mephisto smirked at him, ‘even a formidable tamer isn’t a match for a Demonic King, especially one as riled up as he is.’  
‘Then you shouldn’t have brought him here,’ Yukio snapped angrily and Mephisto gave a deep chuckle.  
‘I’ll let you in on a little secret,’ he murmured, breath warm against Yukio’s cheek, ‘I wanted to test a theory… and besides who am I to deny my precious exorcists when their curiosity pricks them!’ Yukio looked away from him disgusted.   
Amaimon had sat back on his heels, pulling Rin roughly over onto his stomach. Lightning made to sit up, astride him Rin slid into the bend of hips, but Amaimon caught him by the throat and held him against the mattress.   
‘Why don’t you just lay there, Exorcist,’ he hissed softly into his ear. When he was sure the man would not move again Amaimon leaned back yanking Rin’s hips up and twisting his tail around his forearm.  
Rin whined but didn’t dare move too much with his tail pulled taught. Amaimon was leaning over him, nails tracing over Lightning’s forehead. Yukio could see his eyes flicker.   
‘Touch me,’ Amaimon murmured, running a pointed tongue over his sharp incisors. Yukio could see the man’s hands shift to Amaimon’s waist, dexterously unbuckling his belt and sliding down the zip of his jeans. Tan hands began stroking in long deliberate pulls as Amaimon growled low looking down at him.   
Yukio ducked his head, wishing the blood pounding in his ears was loud enough to drown out the sounds of rustling fabric and skin on skin. He jerked up when Rin shouted but Mephisto had grabbed him by the shoulder, sharp nails pricking his skin just slightly.   
Amaimon was bent double over his brother, holding Rin in place by the back of the neck, allowing him to become used to the penetration. Yukio could see his face was flushed and eyes were squeezed shut. Lightning was speaking softly again, his hips cradling Rin as Amaimon started pushing deeper into him.   
‘Look at me,’ Amaimon grunted, pushing back the hair on Lightning’s face and catching a handful as he increasing the pace of his thrusts. Lightning complied, eyelashes flickering when Rin started mouthing his chest.   
Yukio could feel a flush creeping up his throat, suddenly hyperaware of the weight and warmth of Mephisto’s back on his shoulder where he was slouching on the arm of the chair.   
Amaimon gave a throaty growl and Yukio could see Rin was pushing back into him now. He was growling too, low and animal, raising the fine hairs on Yukio’s skin. Lightning was touching him, both hands in between his legs caressing. Amaimon bent, pulling his hair and kissing him again, squashing Rin between.  
Lightning gave a muffled groan, hips pushing up irresistibly into Rin’s stomach. Pressing a clawed hand under Rin, Amaimon licked Lightning’s mouth as he panted, squirming and oversensitive. Amaimon stroked slowly, sharp nails tracing lightly over thin skin, and Lightning hissed through his teeth, back bowing.   
Obviously enjoying the man’s breathless desperation Amaimon hummed. Rin gave a pained whine and Amaimon huffed a breath and shifted, reposing his legs and speeding up the roll of hips. He pulled a still gasping Lightning back to his mouth and stuck a pointed tongue between the other’s lips. Rin was hissing sharply at every downwards thrust. Then he moaned, back arching, and Yukio felt a sudden wave on heat on his skin. It was gone almost as soon as he was aware of it. Mephisto exhaled softly.   
On the bed Rin had gone lax. Amaimon gave a final, deep thrust into him tensing for a moment then stilling. He pulled out of Rin’s limp body.   
Smoothing his silken pyjama shirt, Mephisto stood. From the bed Amaimon growled.  
‘Don’t test my patience at the moment,’ he rumbled before the other could speak.  
‘I’m not done,’ Amaimon told him, eyes gleaming.   
‘You are more than done, baby brother,’ Mephisto muttered, sticking a key into the bedroom door and opening it to reveal his office. Yukio stood too, wondering if there really would be a fight now.   
But after another moment glaring at his brother flatly Amaimon straightened, pulling up his jeans and stumping into the office. The door closed with a soft click.   
‘Go and clean yourself,’ Mephisto ordered removing the key and moving quickly towards the bed. Rin groaned but slowly pushed himself up, moving gingerly away from an inert Lightning. Mephisto stopped short letting him pass.   
Yukio looked after him but didn’t follow, instead turning to watch Mephisto lean over the man on the bed. As he watched Mephisto carefully traced a pattern over Lightning’s forehead. Having been slumped, flushed and glazed exactly where Amaimon had left him, Lightning now gasped rolling to his knees and beginning to cough uncontrollably.   
‘You’re lucky,’ Mephisto muttered as the man convulsed, ‘that blessing hasn’t left you.’ Yukio wasn’t sure lucky was the word he would have used.   
Between Lighting’s fingers Yukio could see he’d coughed up something blackish and oozing. Remembering his training, Yukio moved forwards – realising he was vomiting whatever Amaimon had breathed into him.   
‘Should I…’ he began looking to a frowning Mephisto.  
‘No,’ Mephisto interrupted, ‘he’ll be okay now.’ Lightning drew a rattling breath, wiping the back of his hand across his mouth. He sat hunched on the edge of the bed, a little of the blackish corruption still smeared on his chin.   
‘Are you angry?’ Mephisto asked, looking down at the top of his head.   
‘I don’t think so,’ he muttered, rubbing the back of his neck, and Yukio winced; his voice sounded raw. ‘Did I…?’ he frowned touching the still sticky evidence of an orgasm on his stomach.   
‘I’m not sure,’ Mephisto answered cheerfully, ‘What do you think, Yukio?’   
‘I don’t know,’ Yukio choked, feeling his entire body flush. Lightning was peering at him now. But Yukio was saved further questions but the reappearance of Rin, pale but lucid in his pyjamas.   
‘Rin,’ he said softly turning to his brother.   
‘I’m fine,’ he muttered, though Yukio could see he was holding his body stiffly. Yukio frowned at him but Rin rolled eyes, attention shifting to something over his shoulder. Lightning was watching Rin too, hands gripping his own thighs as though he was struggling to keep himself up right.   
‘Have you stopped being weird now?’ he asked, tail flicking apparently unconsciously.   
‘You started in it, kiddo,’ Lightning chuckled, standing and absently wiping his hands on thighs of his jeans. Without a shirt on and with his unzipped jeans slung low on his hips, he was very lean Yukio could help noticing. Out of the corner of his eye Yukio could see Mephisto inspecting him too.  
‘You’re not injured?’ Mephisto asked, now giving Rin that same assessing look.  
‘No,’ Rin agreed, folding his arms around himself, ‘is that going to happen again?’ He grimaced at Mephisto.   
‘Probably,’ Mephisto shrugged. Rin groaned bowing his head. Yukio sucked his lip looking over his brother sympathetically.   
‘Like I said,’ Mephisto spread his hands, ‘you are what you are.’ Rin groaned again, ‘Let me put you too sleep now,’ Mephisto swept over to him.  
‘I don’t want–’ he started to complain then paused looking at the bed, ‘What’s that black stuff?’   
‘Corruption,’ Lightning answered with a shrug. Mephisto clapped twice and the sheets were replaced with clean polka-dot ones. Rin frowned but apparently having decided he was too tired to argue went and sat heavily on the bed. Folded neatly on the end were what Yukio recognised as Lightning’s now dry t-shirt and jacket.   
‘I won’t tell Suguro you were being weird,’ Rin told Lightning seriously and he laughed.  
‘Thanks,’ he grinned.   
‘You need to sleep,’ Yukio told Rin gently, who sighed but allowed Mephisto to bend over him speaking softly. After a moment Yukio could hear a muffled snore.   
‘Another secret you’re keeping?’ Lightning smirked at Mephisto when he looked up.  
‘Tell the Paladin what you like,’ he grunted, sharp incisors glinting. He remained sitting on the bed beside Rin and Yukio thought he looked somehow duller than before.   
‘The barrier’s really taking it out of you, huh?’ Lightning murmured, tipping his head to the side. Mephisto ignored him standing and turning to the door.  
‘He’ll sleep until tomorrow afternoon,’ he told Yukio over his shoulder, inserting a key into the bedroom door. Yukio had a brief glimpse of an ornate corridor as Mephisto gestured to Lightning.   
‘Thank you, sir,’ he said stiffly as Lightning pulled down his t-shirt and shrugged on his jacket.   
‘Don’t mention it,’ he said cheerfully, trotting past Mephisto, who inclined his head and closed the door with a snap.   
In silence Yukio clicked off the bedroom light. He lay on the polka-dot sheets beside the heavily sleeping Rin and stared up at the ceiling.

**Author's Note:**

> N.B. I used 'Lightning' because 'Lewin' felt too familiar and I thought we'd get get confused with DeathNote if I used 'Light'... and I only found one other fanfic (the search continues!) that mentions him and they used 'Lightning' so yeah :D


End file.
